Fiber cement composite siding is a relatively new and exciting building material that was recently introduced to the United States marketplace. Siding made from fiber cement composite comprises a substrate made up of wood pulp, silica and cement. One big advantage of this type of siding is its great durability. Some manufacturers, in fact, warrantee this product's continued function for up to fifty years. In comparison to shorter-lifetime vinyl or wood siding products this is a great advantage. Traditionally, fiber cement siding is often pre-painted (or pre-finished) in a factory setting and delivered to the job site, for example, in stacks of 8 or 12-foot long sheets. The pre-painted sheets, which may be profiled to look like wood products, or scalloped or cut to resemble shingles, are ready for attachment to the building and yield a primed and/or painted appearance immediately upon being so attached.
Unfortunately, however, fiber cement siding is a much heavier and a much more abrasive substrate compared to wood or vinyl siding products. While builders and homeowners desire the beauty and convenience of pre-painted fiber cement boards, prefinished fiber cement siding products are often visually marred or damaged, either during transit of the siding to the job site or during installation. The damage is often caused as a result of the heavy and abrasive pre-finished boards being rubbed against each other. For example, during installation the quite abrasive bottom surface of one piece of siding is able to easily mar the painted surface of another sheet. This can occur when a sheet being installed on a wall is slid against a sheet that already has been attached to the wall. In another situation the heavy sheets may rub against each other when they are stacked or unstacked. It is quite common that some amount of sliding occurs during these operations. In some cases the siding is packed in a “face-to-face” manner, though this is not always the case when the siding profile does not lend itself to such stacking. Even in these cases the heavy fiber cement siding is prone to visually apparent damage when the sheets are stacked or un-stacked, etc. While not intending to be bound by theory, it is believed that small abrasive particles (e.g., particles that come from the siding) can get between the faces of adjacent sheets and act as abrasive grit against the pre-painted surface. In other cases, the faces of the siding are textured to resemble wood grain. This texture pattern is itself a somewhat rough surface and face-to-face rubbing of the siding might cause abrasion of the pre-painted surfaces. Liners have been used to separate and protect the sheets, however these liners often do not stay exactly between the sheets, thereby allowing an opportunity for the sheets to rub together and become damaged.
Clear coat systems have been used over wood or wood composite substrates. These systems often are “bake finishes” that require heating to a board surface temperature above about 100° C., more typically above about 150° C. Unfortunately, fiber cement has very poor heat transfer characteristics compared to traditional wood or wood composite siding and would require long heat up and cooling times compared to traditional siding substrates. Many pre-finishing lines do not have the oven capacity required to economically process such baked finishes.
From the foregoing, it will be appreciated that what is needed in the art is a pre-finished fiberboard siding product that maintains its factory appearance during transit and normal handling. Such siding products and methods for preparing the same are disclosed and claimed herein.